CHICAGO – A 5-year follow-up of a major randomized trial comparing methods of meniscal tear management in patients with osteoarthritis showed the risk of total knee replacement was 400% greater in patients who underwent arthroscopic partial meniscectomy than in those who received physical therapy alone, Jeffrey N. Katz, MD, reported at the annual meeting of the American College of Rheumatology.

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At 5 years, however, the two divergent initial treatment strategies – arthroscopic surgical repair versus physical therapy – resulted in similar degrees of long-term pain improvement, noted Dr. Katz, a rheumatologist who is professor of medicine and orthopedic surgery at Harvard Medical School, Boston.

“Because that’s the case, a reasonable recommendation – and one that most folks around the world who are thinking about this problem would make – is to have the first choice initially be nonoperative; that is, physical therapy, with surgery reserved for those who don’t improve and who have an interest in undertaking the risks of surgery,” he said.

Dr. Katz presented 5-year follow-up data on 341 participants in the MeTeOR trial, a seven-center study in which middle-age or older subjects with knee pain, a meniscal tear, and osteoarthritic changes on x-ray were randomized to arthroscopic repair or physical therapy. A lot rides on the outcomes of this study, as there is a longstanding debate over the balance of risks and benefits of arthroscopic surgery in this common clinical scenario.

Of the 351 participants, 164 were randomized to and received arthroscopic partial meniscectomy, 109 were randomized to and received a standardized program of physical therapy, and 68 were initially randomized to physical therapy but crossed over to arthroscopic surgery within the first few months because of lack of improvement.

At 5 years of follow-up, all three groups showed similar degrees of improvement in Knee Osteoarthritis and Injury Outcome Score Pain Scale scores, from 40-50 out of a possible 100 at baseline to 20-25 at 6 months, with little change thereafter through 5 years.

The eye-catching finding was the difference in the incidence of total knee replacement (TKR) through 5 years: 10% in those who underwent arthroscopic partial meniscectomy, either as initial therapy or after crossing over from the physical therapy group, compared with 2% in patients who underwent physical therapy alone. Given that more than 400,000 arthroscopic partial meniscectomies are done annually in the United States in patients with knee osteoarthritis, extrapolation from the MeTeOR results suggests an excess of 40,000 total knee replacements in surgically treated patients.

“The higher TKR rates that we observed in surgically treated patients are unexplained, concerning, and require further study. The finding is consistent with the observation in the Osteoarthritis Initiative that TKR rates were higher in patients with arthroscopy as opposed to those treated nonsurgically,” the rheumatologist said.

He proposed two possible explanations for the finding. “It does appear that people who have arthroscopic surgery are then, over the next 5 years, more likely to have total knee replacement. We don’t know whether that is because performing arthroscopic surgery is actually damaging the knee further, leading it to deteriorate more quickly and therefore go on to total knee replacement, or whether when patients develop a relationship with a surgeon and have arthroscopic surgery, they get over some of their apprehension about surgery and may become more likely to accept subsequent surgery for total knee replacement. We hope to find the answer. I think this story is still unfolding because 5 years is a relatively brief period of time in the course of osteoarthritis.

“Arthroscopic surgery certainly offers greater shorter-term improvement, and for some patients that’s worth trading off some downstream risk of joint damage, and for others, they would not want to make that trade-off. So I see it ultimately as a matter of patient choice,” Dr. Katz said.

Knee osteoarthritis affects an estimated 15 million Americans. More than one-half of them have a meniscal tear, the majority of which don’t cause symptoms.

Dr. Katz reported having no financial conflicts regarding MeTeOR, which was funded by the National Institutes of Health.